This handout photo provided by the National Portrait Gallery shows Robert Frost, by Clara Sipprell G …

WASHINGTON (AP) — America often knows the names but not the faces of its great poets. Now the Smithsonian's National Portrait Gallery is introducing dozens of 20th century poets to Washington visitors.

"Poetic Likeness: Modern American Poets" opens Friday and will be on view through April.

Curator David Ward says he wanted to open a poetry exhibit for years because it's a way America defined itself as a culture. Ward says poetry is the language we turn to when something is important.

The show opens with Walt Whitman and maps the evolution of language from the first example of free verse in "Leaves of Grass." Later, Ezra Pound and others develop a unique American voice, separate from Europe.